STAHL 2013 1 28.11.2013 STAHL 2013 Stahlinstitut VDEh Wirtschaftsvereinigung Stahl Stahl in Bewegung Steel in Motion Neue umformtechnische Entwicklungen Neue HSS Arbeitswalzen für die hinteren Gerüste der Fertigstraße von Warmbandwerken Toshiyuki Hattori, Hitachi Metals Wakamatsu, Ltd. Christian Haberkorn, voestalpine Stahl GmbH Nozomu Oda, Hitachi Metals Wakamatsu, Ltd. Nagato Maeda, Hitachi Metals Europe GmbH Roll Development for Hot Strip Mill Finishing Trains Finisher (Earlier) Indefinite chilled 70 80 90 00 10 Adamite High Cr Iron HSS Finisher (Middle Later) Indefinite chilled ICDP Enhanced-ICDP HSS Casting Process Static Centrifugal casting CCC-method * *CCC: Continuous casting process for cladding H1 1
Target of New HSS development HSS Typical example of roll changes Why HSS rolls cannot be used in middle and later stands? Cobble Incident Strip Rolling Direction Reduce roll changes in middle & later stands Back up Roll Stuck strip Stuck strip Cracks Work Roll H2 Rolling Incident Strip sticking Fire cracks Heavy contact stress at the stuck part Crack growth Steel strip sticking : Principal cause of Inferior crack resistance of HSS H3 2
Roll evaluation (Strip sticking): FTS test Weight Rack Specimen Fall Mild Steel Mild Steel Specimen Sticking Surface after test Evaluation of Sticking area Strip sticking Sticking surface ratio (%) Indentation area Roll evaluation (Strip sticking): FTS test Roll Austenized layer Stuck steel (Sticking area) (Indentation area) 100 Roll Austenized layer Stuck steel H4 1mm 200μm Actual roll after cobble FTS test Cross-sectional view of steel stuck Roll surface H5 3
Roll evaluation (wear resistance) : Hot rolling simulator Roll surface Strip sticking evaluation of Conventional Materials wear profile FTS test result Alloy content* mass% Carbide Sticking surface A:Conventinal ICDP <1.0 2-3 28-38 16-36 B:Enhanced ICDP 2.0-2.8 2-3 28-38 16-40 C:HSS1 7.9-8.7 0 15-25 58-79 D:HSS2 10.2-12.28 0 15-25 61-85 *Alloy content: V+Nb+Mo+1/2W B: Enhanced ICDP Matrix ratio Carbide ratio H6 ratio MC D:HSS2 100μm M3C 100μm + ++ + MC 100μm M6C 100μm ++ + - H7 4
Strip sticking evaluation of iron & steel FTS test result Alloy content* mass% Carbide Sticking surface A:Conventinal ICDP <1.0 2-3 28-38 16-36 B:Enhanced ICDP 2.0-2.8 2-3 28-38 16-40 C:HSS1 7.9-8.7 0 15-25 58-79 D:HSS2 10.2-12.28 0 15-25 61-85 E:Spheroidal Iron (SGI) <1.0 6-7 <1.0 4-9 F:Graphitic steel (G-Steel) <1.0 3-4 <1.0 6-19 *Alloy content: V+Nb+Mo+1/2W E: Spheroidal Iron (SGI) F:Graphitic Steel 100μm 100μm Spheroidal graphite and graphitic steel matrix are bainite and martensite by quenching. = same matrix of ICDP and HSS H8 Effect of on sticking resistance 8 6 4 2 Carbide 40 30 20 10 Carbide Cross section microstructure around graphite Stuck material Sticking Ratio % 0 100 80 60 40 20 0 ICDP E-ICDP HSS1 HSS2 SGI G-steel 0 ICDP HSS SGI G-Steel Carbide % ++ + ± % + - ++ Sticking resistance Good Bad Better *SGI::Spheroidal graphite Iron G-steel:Graphitic steel prevent direct contact of roll surface and strip H9 5
Strip sticking evaluation of Developed materials FTS test result Alloy content* mass% Carbide Sticking surface A:Conventinal ICDP <1.0 2-3 28-38 16-36 B:Enhanced ICDP 2.0-2.8 2-3 28-38 16-40 C:HSS1 7.9-8.7 0 15-25 58-79 D:HSS2 10.2-12.28 0 15-25 61-85 E:SGI <1.0 6-7 <1.0 4-9 F:G-steel <1.0 3-4 <1.0 6-19 G:Development 1 4.2-5.0 2-3 24-34 18-37 H:Development 2 7.0-7.8 2-3 22-32 18-33 *Alloy content: V+Nb+Mo+1/2W MC H: Development 2 Enhanced ICDP 100μm Conventional HSS Microstructure comparison and other properties 12 H10 Compressive residual stress Fracture toughness : Development 2 Enhanced ICDP (<<HSS) :Development 2 Enhanced ICDP Anti-crack resistance of developed roll is same level as Enhanced ICDP H11 6
Wear resistance evaluation (Hot rolling simulator) 13 Poor 60 Alloy content: V+Nb+Mo+1/2W Wear amount Alloy content 12 Wear Amount μm Excellent 50 40 30 20 10 0 Conclusions Conventinal Enhanced ICDP ICDP HiCr Iron HSS1 HSS2 Development 1 Development 2 GS HSS A new type of HSS roll for later stands in Hot Strip Mills GS HSS, which has same level of strip sticking resistance and two times or more resistance as ICDP has been developed. is effective element for strip sticking resistance. New type of wear and strip sticking resistant HSS roll has been developed, which contains and carbide forming elements such as V, Nb, Mo and W. Developed rolls are showing excellent performance in actual hot strip mills. Patent applications covering the developed roll have been applied in countries all over the world. 10 8 6 4 2 0 Alloy Content mass% H12 H13 7
GS-HSS experience at voestalpine voestalpine Stahl GmbH www.voestalpine.com/stahl Hot-strip Mill V1 N S Zunderwäscher FS Zunderwäscher VG N S Mill stands Rougher Work roll diameter Work roll quality Distribution Performance t/mm R1 1100-980 mm Semi-HSS/ Hi.Cr. 20/80 15.000/13.000 Finisher F0 780-680 mm HSS/ Hi.Cr. 50/50 16.000/7.000 F1 780-680 mm HSS/ Hi.Cr. 50/50 16.000/7.000 F2 780-680 mm HSS/ Hi.Cr. 50/50 16.000/7.000 F3 780-680 mm HSS/ Hi.Cr. 50/50 16.000/7.000 F4 725-625 mm E-ICDP /GS-HSS 90/10 5.000/9.000 F5 725-625 mm E-ICDP /GS-HSS 90/10 5.000/9.000 F6 725-625 mm E-ICDP /GS-HSS 90/10 5.000/9.000 voestalpine Stahl GmbH 10.12.2013 8
Comparison of roll performance in F4 conventional rolls versus GS-HSS trial V2 voestalpine Stahl GmbH 10.12.2013 Actual roll performance comparison Silicon steel V3 voestalpine Stahl GmbH 10.12.2013 9
Actual Roll performance comparison All steel grades V4 voestalpine Stahl GmbH 10.12.2013 STAHL 2013 Stahl in Bewegung Steel in Motion Neue umformtechnische Entwicklungen THANK YOU FOR YOUR ATTENTION Toshiyuki Hattori, Hitachi Metals Wakamatsu, Ltd. Christian Haberkorn, voestalpine Stahl GmbH Nozomu Oda, Hitachi Metals Wakamatsu, Ltd. Nagato Maeda, Hitachi Metals Europe GmbH 20 28.11.2013 STAHL 2013 Stahlinstitut VDEh Wirtschaftsvereinigung Stahl 10